Motion converting mechanism



Nov. 23, 1954 A. BLACKBURN 2,694,933

MOTION CONVERTING MECHANISM Filed Nov. 5, 1949 4 Sheets-Sheet l Z3INVE/WUR 23 A; LUTHER A. BLACKBURN A TTORA/EVS Nov. 23, 1954 A.BLACKBURN 2,694,933

MOTION CONVERTING MECHANISM Filed Nov. 5, 1949 4 Sheets-Sheet 2//Vl//VTOR /6 LUTHER A BLACKBURN A TTORNEVS Filed NOV. 5, 1949 1954' A.BLACKBURN 2,694,933

MOTION CONVERTING MECHANISM 4 Sheets-Sheet I5 2 Z; w LUTHER A. g ii fim-1 W: W

Nov. 23, 1954 2., A. BLACKBURN 2,694,933 MOTION CONVERTING MECHANISMFiled Nov. 5, 1949 4 Sheets-Sheet 4 fmz @111 //V [/5 N TOR LUTHER A.BLACKBURN ATTORNEYS United States Patent MOTION CONVERTINGMECHANISMLuther A. Blackburn, Eagle Rock, Calif. Application November's, 1949,SerialN-o; 125,769

11 Claims. 1 (Cl. 74-37) This invention relatesto deep -well. pumps andmore specifically contemplates'long strokezpumping apparatus adaptedparticularly for oil wells.

in pumping deep wells, the resilience of'thepump rod string by which thepump isactuated, and ofthetubing string through which the fluid raisedby thepump is conducted to well surface, resultsin very substantiallydissipating the effective stroke of the pump plunger as-the weight ofthe fluid column is alternately transferre'd'from the rod string to thetubing string and vice versa at the end of each stroke. Accordingly, inorder to obtain maximum eificiency, pumping equipment has been devisedto provide for a stroke of a length sufficient to min-imize' the effectof elongation and contraction ofthe tubingand rod strings duringoperation. One form of such equipment which possesses numerousadvantages, comprises a crosshead, to which the rod string'is connected,reciprocated vertically by means of endless chains. Ieretofore in orderto obtain the essential'balance of the crosshead and avoid its lateralthrust against the frame and pump rod, four pump-actuating chainshavebeen required. 'While such equipment is very effective the initial costof-such devices, is for many applications, exorbitant.

The present invention is concerned primarily with a chain-actuatedpumping jack embodying only a-single pair of chains operable-to actuatethe pump during its effective or pumping stroke and to idle'on theoppositestroke of the pump plungenthe weight of' the fluid-column and ofthe rod string being utilized to lower the pump rodin the well onalternate strokes.

More specifically, a principal object'of the presentinvention is toprovide a long stroke deep well'pumping' jack comprising essentially anupright frame-for the' verticallyguided movement of a pump rod clampingassembly, reciprocated in response to movementofalternatereaches of asingle pair of vertically disposed endless chains, and the weight of thefluid column'in the well, the movement of the chains being transmittedto the clamping assembly during the pumping stroke through a pivotedassembly adapted to follow the chains throughout their circuits.

Another and highly important-object hereof'is to provide achain-actuated pumping jack wherein the upwardly moving reaches of thechain are disposed in diametric alignment but at opposite sides of therod string to be actuated and are connected to the latter-by pivotedarms adapted to assume a parallel relationship with the direction ofmovement of the actuating elements-of the-chains and the rod stringduring the pumping stroke.

Another object is'to provide a method of, and apparatus for, pumpingdeep wells, in accordance withwhich the weight of the pumping rod stringand fluid column in'the tubing string is partiallybut not whollycounterweighted during the effective or upper stroke of the rod string,and the diflerence between the weight of the rod'string,'and thecounterweight is utilized to actuate theipump duringits opposite stroke.

Another highly and important objectis'the'provision of a chain actuatedpumping jack'of'the character referred to embodying acounterweightvertically reciprocable in the frame and operable'tooppose theweight ofthefiuicl column in the tubing string through a pair of chainspassingover sprockets in the crown'blo'ck'and connected to the rodstring, the sprockets being keyed together whereby the'counterweightopposes anylate'ral'thru'st'imposed upon the pumprodbythe'pump'actuating'mechanism.

Another object isthe provisionofmeans to resiliently absorb the weightof the fluid column in the well at the lower end of the stroke as thechains pick up the load, and to relieve in a similar manner the rodstring of the weight of the fluid at the upper end of the stroke.

Another object is to provide means for elevating the jack upon theroller for-facile movement of the unit from an operative positionoverthe well to a position laterally of the well so as to provide servicingof the pumping equipment, cleaning of the casing string and replacementof the rod string, tubing and pump barrel.

Other objects and salient features of my invention, such as simplicityof construction, economy of manufacture, facility of servicing,adjustabilit'y to meet the requirements of specific installations, andmaximum efiiciency per unit of power, will be apparent to those of skillin the art upon an examination of the following description read in thelight of the accompanying drawings, in which:

Fig. l is a side elevation, partially broken away, of a pumping jackembodying my invention;

Fig. 2is an elevation of the apparatus taken at right angles to the viewof Fig. 1;

Fig. 3 is a perspective view of the pump rod guide and supportingassembly illustrating the connection thereto of the actuating mechanismand counterweight chains, the parts being in their respective positionsassumed during theup stroke of the pump rod string;

Fig. 4 is a side elevation of the pump rod supporting mechanismillustrating one of the pivoted arms in the position which it assumes onthe down stroke of the rod string;

Fig. 5 is a horizontal sectional view of the frame showing the upperdrive sprockets of the actuating mechanism and-the relationship of thecounterweight guides, omitting the rod string, its supporting assemblyand the counterweight;

Fig. 6 is an enlarged elevation, partially broken away, of one of theupper sprockets for the drive chain, depicting particularly the means bywhich the tension of the chain, associated therewith, is adjusted;

Fig. 7 is a broken horizontal sectional view through the vertical guidesof one of the adjustable mountings for the upper sprockets; V

Fig. 8 is a sectional view similar to Fig. 7 taken through the adjustingscrew of the upper sprocket supporting mechanism and showing thestationary block relative to which the upper sprockets are shifted;

Fig. 9 is an end elevation of one of the rails, also showing inelevation the means'by which the frame is elevated upon rollers tofacilitate the shifting of the frame onto and ofi' the well;

Fig. 10 is a broken side elevation of the assembly shown in Fig. 9;

Fig. 11 is a frame;

Fig. 1-2 is an exploded elevation of one of the lower sprocketassemblies;

Fig. 13 is a side elevation of the pivoted arm assembly associated withthe rod string clamp and guide mechanism depicting particularly the yokeelements for pivotally engaging the respective actuating chains;

Fig. 14 is a fragmentary view of the brake assembly showing the drivesprocket in broken section;

Fig. 15 is a vertical sectional view through the counterweight sprocketand pulley assembly illustrating the keying'of these parts upon a commonshaft.

Referring to the drawings more in detail, the numerals of which indicatesimilar parts throughout the several views 15 designates each of aplurality of sills covering the pit of an oil well and 16 and 17 referto the casing and tubing strings, respectively, of the well proper. 18indicates a conventional tubing head through which the polish rod 19 tobe actuated reciprocably projects. Mounted on the sills 15 in parallelrelation and equispaced to opposite sides of the well are a pair ofrails 20 upon which the'pumping jack, embodying 'myinvention issupported. The frame of the structure comprises two channel irons 21 andtwo angle from 22, vertically disposed and arranged at the corners,respectively, of a rectangle which is slightly narrower than thedistance between the rails 20. The channel 21 and the vertical angleiron frame member 22 at each side of the structure perspective view ofthe counterweight parallel to the respective rails are mounted upon acommon horizontal angle iron 23. The vertical disposition of thechannels 21 is reinforced by a pair of inclined braces 24 having theirlower ends mounted upon extensions of the angle irons 23, respectively.The frame is further reinforced by a plurality of channels 25 and angleirons 26 extending between the vertical channels 21 and complementaryangle irons 22 which together define the corners of the frame.

The cross-sectionally rectangular form of the top of the frame ismaintained by a crown block 27 comprising angle irons 28 bolted orotherwise rigidly secured between the upper ends of the vertical angleirons 22 and channels 21. At each of the four corners of the crown block27 an upstanding perforated lug 29 is secured to facilitate the removalof the block when required, or the lifting of the entire unit fortransportation.

Each of the lower horizontal angle irons 23, forming the foundation ofthe frame structure, is welded to the side of an elongated box frame 30,comprising a pair of channel irons 31 having their edges opposed andwelded together. The box frames are normally supported upon therespective rails 20 but are adapted to be elevated from the latter inresponse to the manual lowering of rollers 32 housed within the boxframes. Four rollers 32 are provided, each being flanged so as to engageopposite edges of the rail 20 with which it is associated so as toprevent lateral displacement of the structure with respect to the well.Each of the rollers 32 is journalled upon a shaft 33, having its endsmounted in the legs of an inverted U-shaped retainer 34. The rollers 32and the retainers 34 in which the former are journalled, respectively,are disposed within the elongated box frames adjacent the four cornersof the pump jack and are secured against longitudinal displacementwithin the respective box 00 frames by a series of stud bolts 35 whichextend through vertical slots 36 formed in the sides of the opposingchannels 31 of each box frame 30 and adjoining angle irons 23 and arethreaded in the respective retainers 34. Thus each retainer and theroller 32, rotatably mounted therein, is vertically reciprocablerelative to the box frame 30 and the superstructure of the pump jack.The lower periphery of each of the rollers 32 projects through a loweropening 37 in the channels 31 of which the box frames are composed andis normally held in contact with the rail therebelow by pressure appliedto the upper surface of the retainer 34 by a bearing member 38.Interposed between the bearing member 38 and retainer 34 are a series ofball bearings 39 to facilitate relative rotation between the member 38and retainer. The bearing member 33 is formed integrally with the lowerend of a screw 40 threaded through a nut 41, non-rotatably fixed at thetop of the box frame 31. A capstan 42, rigidly secured to the upper endof the screw 40, enables manual rotation of the latter and of thebearing member 38, in an obvious manner, so as to elevate the adjacentend of the box frame and the corresponding corner of the jack relativeto the rail 20 and roller 32. With each corner of the pumping jack thusraised upon the rollers 32 the entire unit may be rolled upon the rails20 to a position laterally of the well when occasion demands.

At one side of the well a concrete foundation 43 is provided for a powerunit. Superposed upon the foundation 43 are a pair of I-bearns 44, heldin parallel, spaced relationship by a spacer plate 45. Securely mountedupon the I-beams is an engine 46 for actuating the pumping mechanismhereinafter described. The engine 46 is normally held in adjustedposition upon the foundation 43 but may be shifted laterally withrespect to the well by four screws 47 which are threaded through lugs48, mounted to the foundation and bearing against the ad jacent I-beam44. The pulley 49 of the engine 46 is connected to a drive pulley 50 ofthe pumping jack by a belt 51, both pulleys 49 and 50 and belt 51 beingpreferably enclosed in a housing 52 to prevent injury to workmen duringoperation of the unit. The drive pulley 50 of th: jack is keyed upon ashaft 53, journalled in bearings 54 carried by a mounting plate 55,projecting laterally from the frame of the jack and welded or otherwisesecured to the vertical channel 21 and angle iron 22, defining theadjacent side of the jack frame.

At the level of the pulley shaft 53 and at each side of the frameforming a right angle with the shaft is a transverse vertical plate 56welded or otherwise secured across the vertical channels 21 and angleirons 22, respectively.

Rotatably supported by each of the plates 56 is a drive sprocket andgear assembly adapted to be actuated from the pulley shaft 53 by apairof spur gears 57, splined to the shaft in alignment with oppositesides of the jack frame. Each sprocket and gear assembly (illustrated inFig. 12) comprises a stub shaft 58, secured rigidly in a suitable mannerto the adjacent plate 56 so as to pro ect into the frame. A pair ofroller bearings 59 carried by each shaft 58 rotatably mount a gear 60which is held in mesh with one of the pulley-shaft pinions 57 at thecorresponding side of the unit. The hub of the gear 60 projectslaterally and is formed with a fiat surface against which a chain drivesprocket 61 is attached by a series of screws 62. The gear 60, sprocket61 and the bearings 59 for the same are held on the stub shaft 53 by adisk 63 secured to the end of the shaft by a pair of screws 64.

Endless drive chains 65, engaged with the respective sprockets 61 aresupported in the upper end of the jack by idler sprockets 66. Each ofthe sprockets 66 is journalled upon a stub shaft 67 projecting laterallyfrom a slide 68, engaged between a pair of vertical channels 69, weldedat their lower ends in spaced, opposed relation to the cross brace angleiron 26. A hub spacer 70, encircling the shaft 67 between the sprocket66 and slide 68 maintains the sprocket in the vertical plane of thedrive sprockets 61 therebelow for the corresponding chain 65. Thesprocket 66 and slide 68 at each side of the frame are movablevertically to determine the proper tension of the chain 65, relative toa block 71, securely fitted between the guide channels 69 at theadjacent side of the frame. A screw 72, threaded upwardly through theblock 71, is adapted to bear against the under side of the slide 68 andsupport the same in accordance with the adjustment of the screw 72. Theadjusted position of the slide 68 is reinforced by a clamping plate 73of a width sufiicient to overlie the outer edges of the opposed channels69 and is attached to the slide 68 by screws 74. Thus each of thesprockets 66 may be elevated, upon relieving pressure of the clampingplate 73 on the channels 69, incident to the threaded adjustment of thescrew 74.

It will be observed that the upper and lower sprocket assemblies for thechains 65 are supported in positions which locate complementary verticalreaches of the chains in diametric alignment with the vertical center ofthe pumping jack. Thus, with the box frames 30, defining the bottom ofthe pumping jack, equi-spaced at opposite sides of the well, the polishrod 19 of the pump, projecting upwardly through the tubing head 18 ofthe well, will extend directly between these reaches of the chains 65.

The chains are operatively connected to the polish rod 19 of the pump bya cross frame 75, reciprocably mounted within the vertical frame of thejack. This mechanism illustrated more clearly in Fig. 3 comprises a pairof bars 76, arranged in parallel, spaced relationship, and uprightmembers 77, connected, respectively, to opposite ends of each of thebars 76. The upper end of the frame 75 is defined by a yoke 78, toopposite sides of which the uprights 77, at each side of the frame, aresecured. The yoke 78 is provided with an intermediate arcuate offsetportion 79 to permit upward projection of the polish rod 19, whenrequired, as will appear. The bars 76 defining the bottom of the crossframe 75 are maintained in spaced relationship by a saddle plate 80,secured across the bars 76 intermediate their ends, and between oppositecorresponding ends of the bars, a roller 81 is journalled. Similarly aroller 82 is journalled between the upper ends of each pair of opposeduprights 77. The rollers 81 and 82 of the pair at each side of the crossframe 75 project laterally of the frame for operative engagement withguide channels 83, respectively, which are rigidly mounted in verticalposition, in opposed relationship, to the cross braces 25 at theopposite sides of the frame which are parallel to and mounted upon therespective rails 20. Thus the cross frame 75 is vertically reciprocablebetween the channels 83 in the plane of the polish rod 19 which, uponoperative assembly of the unit, projects upwardly between the bars 76forming the lower part of the cross frame. The saddle plate 80 is formedwith a central opening 84 to accommodate the polish rod 19 and forms aseat for a helical spring 85 encircling the rod. The upper end of thespring 85 is covered by a circular plate 86 through which the rodprojects and 7 upon which a rod clamp 87 of conventional construction,

engaged with the polish rod, is adapted to bear. Thus the Weight of therod string 19 is resiliently transmitted to the cross frame 75 by thespring 85.

Projecting laterally from .the outer surface of each lower bar 76 of thecross frame 75 is a stub shaft 88 which isengaged by a bearing 89rigidlysecured to the lower end of a chain arm 90. The upper ends of the arms90 are connected. by a transverse bearing mounting 91 (Fig. 13) belowthe yoke'78 of the frame 75. A self-aligning bearing 92 carried by themounting 91 provides rotatable support fora rod 93 which extendslaterally above the ends of the arms 90 into the line of movement of therespective chains 65. The ends of the rod 93 are formed with lateral cutouts 94 to provide chain yokes 95 which partially encompass and aresecured to horizontally-aligned complementary links 96 of the respectivechains by pins 97.

It will be observed that upon actuation of the chains 65 by the powerunit the cross frame 75 will be elevated during upward movement of thelinks 96 of the chains 65 with which the double-yoked rod 93 isconnected, this movement being transmitted through the arms 90 to thebars 76 of the cross frame 75. No lateral thrust is developed duringthis movement due to the parallel reiationship between the arms 90,upwardly moving reaches of the chains 65 and the pump rod string 19. Asabove indicated the upward movement of the cross frame 75 is transmittedto the polished rod 19 and the pump so as to elevate the fluid column inthe well incident to actuation of the pump on its effective stroke. Uponreaching the upper sprockets 66 the double-yoked rod 93 is swunglaterally so as to follow the links 96 to which it is connected over thesprockets, the arms 90 pivoting on the stub shafts '88 which projectfrom the lower end of the cross frame 75. Due to the angular dispositionof the arms 90 during downward movement of the links 96 to which the rod93 is connected, any tension by the chains 65 upon the arms 90 duringthe lowering of the rod string would tend to exert a lateral thrust uponboth the polished rod and cross frame 75 and accordingly, as ishereinafter more in detail described, the weight of the rod string andthe fluid column in the tubing string is utilized to lower the crossframe.

In order to further obviate any objectionable results from theapplication of excessive power to the chains 65 during the downwardstroke of the pump, I provide arcuate cut outs 93 in the inner edges ofthe uprights 77 at the cross frame 75 toward which the arms 90 areinclined during the downward movement of the cross frame in order toaccommodate the double-yoked rod 93 of the frame assembly. The crossframe is so proportioned relative to-the disposition and diameters ofthe sprockets to compel the double-yoked rod 93 to bear against thelower arc of the cut outs 98 during the downward movement of the frameand thereby directly transmitthe tension of the chains 65 to the framethrough the uprights 77 in which the cutouts are formed.

Upon reaching the lower arcs of the drive sprockets 61 the rod 93 of theframe assembly moves with the links 96 to which it is connected, intothe upwardly moving reachesof the chains 65, returning the arms 90 to avertical position. In order to stabilize the pivoted arms as the load,comprising the weight of the rod string 19 and fluid column is picked upby the chains and to minimize oscillation of the pivoted arms 90 at thisstage of the cycle of operation, the lower bars 76 of the cross frameare provided with a pair of lugs 99 against which flanges of thebearings 89 at the lower ends of the arms 90 abut as the arms re-assumevertical position. It will be observed that the shock upon the rodstring 19 and pump actuating mechanism of assuming the load is absorbedin part by the spring 85 interposed between the polished rod clamp 87and cross frame saddle plate 80 It will be observed that the offset 79in the yoke 78 permits projection of the rod string above the crossframe when the pivoted arm assembly is laterally displaced so as tofacilitate adjustment in the effective length of the pump rod as well asinitial operative assembly of the unit on the well.

In accordance with the preferred construction the pump rod string andfluid column in the well are partially counterweighted. Thecounterweight 100 is composed of a plurality of fiat weights 101,rectangular in plan, which are suspended in vertical series in acounterweight frame 102, vertically reciprocable betweencorrespondingly-disposed guide rails at the side of the pumping jack.The vertical guides for the counterweight frame 102 are composed ofthe-two'an-gle irons i22- of the pump jack frame properand twoadditional vertical angle irons 103, arranged to define the corners ofatrectangle only slightly larger than the dimensions of-the frame 102 tobe accommodated. The counterweight frame comprises a pair of side plates104'havingtheir vertical edges enclosed in angle iron wear'members105,and a transverse bottom 106 welded or otherwisesecured between the sideplates 104, for the support of the weights 101. At the upper end of thecounterweight frame 102 are a pair of transverse channels 107 arrangedwith their backs in opposition to one another and inspaced relation,their ends being rigidly connected to the respective side plates 104.The ends of a pair of counterweight chains 108 extend downwardly fromthe top of the unit between the channels 107 and are secured to metalstraps 109 which are bound firmly to a cushioninghbar 110 at pointsoffset but equi-spaced from the vertical center of the frame. The endsof the bar 110 project into vertical slots 111 in the respective sideplates 104 of the counterweight frame whereby the bar 110 and chains 108may be raised or lowered relative to the counterweight frame 102 and theweights 101 carried thereby. The bar 110 is normally maintained in thelower extremities of the slots 111 by a series of helical springs 112,interposed between the bar 110 and the channels 107 thereabove, thesprings 112 being adapted-to compress slightly in response to suddentension upon the chains, as will appear. It willbe appreciated that thesprings of the counterweight frame supplement thefunction of the spring85 in absorbing the shock of the reversalof the movement of the crossframe and pump rod.

The chains 108 extend upwardly to the top of the pumping jack where theypass over a pair of sprockets 11-3, keyed in exact alignment on a commonshaft 114, as indicated at 140 (Fig. 15) which is journalled in bearings115 supported on beams 116 carried by the angle irons 28 connectedbetween the upper ends of the verticals 21 and 22. The sprockets 113 forthe counterweight chains 10% are offset with respect to the middle ofthejack frame so as to locate the innermost arcs of the sprockets inalignment with the plane of the channels 83 between which the crossframe 75 reciprocates. The reaches of the chains 108 depending from theinner lateral .arcs .of the respective sprockets 113- are connected attheir lower ends by suitable straps 117 to the yoke 78 of the crossframe '75 at opposite sides of the offset 79 therein. It will thus beseen that the total weight of the counterweight assembly beingtransmitted over the sprockets 113 at the top of the pump jack to thereciprocating cross frame 75 opposes the weight of the rod string 19 andof the fluid column in the well. In accordance with the preferred methodof operation'and utility of apparatus of the type hereinabove described,weights 101 are added to the counterweight frame 102 until the totalweight of this assembly balances the well load and then weights areremoved until the engine idles on the downstroke. In order to avoiddamage to the equipment or possible injury to workmen, safety means isincorporated in the unit to prevent a fall of the counterweight frame102 in the event of fracture of the chains 108. 'For this purpose,cables 118 are suspended from pulleys 119 keyed to the sprocket shaft114 adjacent the respectice sprockets 113. Corresponding outer ends ofthe cables 118 are secured by suitable means to the straps 109 by whichthe counterweight chains 108 are connected to the cushioning bar 110 ofthe counterweight frame 102. The inner opposite ends of the cables 118are similarly attached to the yoke 73 of the cross frame 75 adjacent therespective chains 102 and in alignment with the pulleys 113 from whichthey depend. It will be understood that the cables 118 are lax and donot normally support the counterweights 100. Should either of the chains108 break, however, thecables 118 are under sufficient tension toimmediately assume the load and avoid both the binding of thecounterweight frame 102 in the guide angle irons 22 and 103 as well asinadvertent gravitation of both the counterweight frame and the crossframe 75.

The counterweight sprockets 113 and pulleys 119 are enclosed by a cover120 supported on the crown block 27. 121 indicates the ladder secured tothe side of the frame, and 122 a railing mounted upon the crown block 27to facilitate access by workmen to the various working parts.

With the cross frame in which the polish rod 19 is clamped at the lowerend of its stroke the counterweight frame 102 is disposed adjacent thetop of its range of movement. As the weight of the counterweightassembly is less than that of the combined weight of the rod string andfluid column, power from the engine 46 is required to actuate the chains65 and elevate the cross frame and polish rod on the effective stroke ofthe pump. As the pivoted arms 90 reach the top of the stroke and swingover the upper arcs of the idler sprockets 66 the counterweight framewill be at the bottom of its range of movement. At the beginning of thedown stroke the weight of the fluid in the well is transferred to thetubing string, but as the remaining well load, including the weight ofthe rod string, is slightly in excess of that of the counterweights, therod string will, during the down stroke, gravitate at a velocitysubstantially equal to that of the movement of the rod string inresponse to the power of the engine during the upstroke. With the unitbalanced as above described, the engine merely idles during the downstroke of the pump rod. At the beginning of the upstroke the engine isreactivated by conventional control mechanism to assume the greater loadwhich includes the weight of the fluid in the well as the momentum ofthe drive mechanism is dissipated.

In order to further control the velocity of operation of the device andto provide a safety factor in the event of the breaking of thecounterweight chains and cables 118 or rod string, I provide a manuallyoperable brake mechanism (Figs. 1 and 14) adapted to frictionally engagethe internal surface of the rim of the drive pulley 50, comprising abrake shoe 123 pivoted at 124 to a suitable bracket mounted to the sideof the frame. The opposite end of the brake shoe 123 is engaged by aneccentric 126 formed integrally with the end of a brake rod 127,journalled in bearings attached to the side of the frame. A lever 128,secured rigidly to the brake rod 127 is engaged by linkage 129 extendingdownwardly to adjacent the bottom of the jack, where a suitable manuallyoperable brake lever assembly 130 of conventional construction isprovided to exert tension upon the linkage 129. The swinging of thelever 128, incident to tension of the linkage 129, is effective to turnthe brake rod 127 and actuate the eccentric 126, putting pressure uponthe brake shoe 123 and through it, creating friction with the pulleyrim. It will be appreciated that the brake mechanism may be controlledand actuated by well known mechanism in response to an excessiveincrease in the velocity of movement of the pump rod.

Effective operation of chain-actuated pumping units of the charactercontemplated depends upon continuous and effective lubrication of thedrive chains 65 as well as of the counterweight chains 108. The presentinvention contemplates the incorporation of a force-feed lubricatingsystem comprising a pump 131 mounted upon a bracket 132 secured to theside of the frame below the pulley shaft 53. The pump 131 is actuated bya belt drive 133 from a pulley 134 carried by the end of the main pulleyshaft 53 so as to force a continuous flow of oil through four tubes 135leading to the drive sprocket 61, idler sprockets 66 and counterweightchain sprockets 113, respectively. Each of the tubes 135 terminatesabove the upper arc of the sprocket with which it is associated so as tocontinually direct oil onto the sprocket as the same are turned inresponse to rotation of the pulley shaft 53. The drive chains 65 andsprockets 61 and 66 are par tially protected from dust, sand and otherdebris by a pair of shields 136 and 137, mounted vertically within theframe and partially encircling opposite sides of this mechanism.

Another feature of the invention resides in the provision of a shortsection 19a of polish rod within the cross frame 75. The section 19a mayremain permanently in the cross frame even while moving the unit on andoff the well. To this end, the section 19a is of a length sufficient toextend below the lower edges of the plates 56 when the cross frame is inits lowermost position. The lower end of the section 19a is connected tothe polish rod 19 by a conventional coupling 138.

In preparing the unit for movement from the well over the rails 20 thecross frame 75 is lowered until the coupling 138 is below the plates 56whereupon a rod clamp such as that shown at 87 in Fig. 3, is engagedwith the rod 19 immediately above the tubing head 18 for the support ofthe rod string in the well. Thereafter, the polish rod 19 and section19a are disconnected at the coupling 138, and the belt 51 isdisconnected from the drive pulley, whereupon the unit is ready to bemoved without the necessity of disturbing the tubing head 18.

While the embodiment illustrated and described represents a preferredconstruction of a pumping jack embodying my invention, it will beappreciated that numerous changes in size, design, shape, number andproportion of the various parts may be made, and that the arms 30 may bepivoted directly to a suitable clamp for the rod string and the latterguided in its vertical movement by structurally separate auxiliarymeans, thus dispensing with the cross frame, without departing from thespirit of my invention as defined by the appended claims.

What I claim and desire to secure by Letters Patent is:

1. In a pump unit of the character described, a crosshead, an uprightframe to guide said crosshead for vertical reciprocation, a polish rodclamp carried by said crosshead, a pair of endless chains disposed atopposite sides of said crosshead, means to move upwardly reaches of saidchains located at diametrically opposite sides of said polish rod clamp,and a pair of arms pivotally connected to said crosshead and to saidreaches, respectively, of said chains, the upwardly moving reaches ofsaid chains being disposed in a common vertical plane substantiallycoinciding with the axis of pivoting of said arms to said crosshead.

2. In a pump jack, a pair of chains, a pair of verticallyalignedsprockets supporting each of said chains, means to actuate saidsprockets to move corresponding vertical reaches of said chains,upwardly, a crosshead vertically reciprocable between said upwardlymoving reaches of said chains, a pair of arms pivoted to said crossheadat points located between the vertically moving reaches of said chains,and means to pivotally connect said arm to said upwardly moving reachesof said chains, respectively.

3. In a pump jack for reciprocating a sucker rod string for actuating apump in a well, a vertically movable crosshead, a polish rod clampcarried by said crosshead for engagement of said rod string, meanscomprising an endless chain to reciprocate the crosshead, including anarm pivoted between said crosshead and said chain, the point of pivotingof said arm to said chain being disposed in a vertical plane coincidingwith the axis of pivoting of said arm to said crosshead during theupstroke of said crosshead and movable out of said plane during the downstroke of the crosshead.

4. In a pump jack for reciprocating a sucker rod string for actuating apump in a well, a vertically movable crosshead, a polish rod clampcarried by said crosshead for engagement of said rod string, meanscomprising an endless chain to reciprocate the crosshead, including anarm pivoted between said crosshead and said chain, the point of pivotingof said arm to said chain being disposed in a vertical plane coincidingwith the axis of pivoting of said arm to said crosshead during theupstroke of said crosshead and movable out of said plane during the downstroke of the crosshead, and a counterweight to substantiallycounterbalance the weight of the rod string on the downstroke of thelatter.

5. In a pump jack for reciprocating a rod string in a well, a crosshead,means to guide said crosshead in vertical movement, a rod clamp carriedby said crosshead to engage said rod string, a pair of endless chains,each comprising an upwardly-moving reach and a downwardly moving reach,said chain being operatively disposed with the upwardly moving reachesthereof located at diametrically opposite sides of said rod clamp, apower unit to actuate said chains, and arms pivoted to said crossheadand connected to said chains to transmit movement of said upwardlymoving reaches of said chains to said crosshead and rod clamp, theupwardly moving reaches of said chains being disposed in a verticalplane coinciding with the axis of pivoting of said arms to saidcrosshead.

6. In a pump jack for reciprocating a rod string in a well, a crosshead,means to guide said crosshead in vertical movement, a rod clamp carriedby said crosshead to engage said rod string, a pair of endless chains,each comprising an upwardly-moving reach and a downwardly moving reach,said chains being operatively disposed with the upwardly moving reachesthereof located at diametrically opposite sides of said rod clamp, apower unit to actuate said chains, means to transmit the movement ofsaid upwardly moving reaches of said chain to said crosshead and rodclamp, and means to substantially counter- 9 balance the weight of therod string on the downward stroke of said crosshead.

7. In a pump jack, a crosshead comprising a frame, a shaft pivoted insaid frame, a pair of arms carried by said shaft for pivotal movementrelative to said crosshead, a bearing carried between said arms, amember extending through said bearing, a pair of chains to verticallyreciprocate said crosshead, and means to pivotally connect said chainsto the ends, respectively, of said member.

8. In a pump jack for reciprocating a rod string, a frame, a crossheadvertically reciprocable in said frame, means carried by the center ofthe crosshead engaging the rod string to be reciprocated, meanscomprising an endless chain to reciprocate the crosshead, including anarm pivoted between said crosshead and said chain, the point of pivotingof said arm to said chain being disposed in a vertical plane coincidingwith the axis of pivoting of said arm to said crosshead during theupstroke of said crosshead and movable out of said plane during thedownstroke of the crosshead, a counterweight vertically reciprocal insaid frame, a shaft journaled in the upper portion of said frame, a pairof sprockets fastened to said shaft to rotate in unison with the shaft,a pair of chains passing over and engaged with the respective sprockets,and connected between said crosshead and said counterweight, said chainsbeing connected to said crosshead at points equispaced from and atopposite sides of said first-named means, to balance the crossheadduring operation.

9. A pump jack according to claim 8 in which the teeth of the sprocketsare in the same time relationship with each other.

10. In a pump jack for reciprocating a sucker rod string for actuating apump in a well, a vertically movable crosshead, a polish rod clampcarried by said crosshead for engagement of said rod string, meanscomprising an endless chain to reciprocate the crosshead, including anarm pivoted between said crosshead and said chain, the point of pivotingof said arm to said chain being disposed in a ver tical plane coincidingwith the axis of pivoting of said arm to said crosshead during theupstroke of said crosshead and movable out of said plane during the downstroke of the crosshead, a power unit to actuate said chain mechanism,and a counterweight to counterbalance slightly less than the entire loadof the rod string during the down stroke of the rod string so as topermit said power unit to idle during alternate strokes of the pump.

11. Apparatus according to claim 7 in which the frame has anindentation, and on the upstroke of the crosshead the arms are pulledinto a vertical plane by the chains, and on the downstroke of thecrosshead the arms pivot out of the vertical plane so that the memberrests in the indentation, whereby the arms are provided with stabilityduring the downstroke.

References Cited in the file of this patent UNITED STATES PATENTS 25Number Name Date 269,775 Cannon Dec. 26, 1882 1,756,089 Hunter Apr. 29,1930 1,774,321 Detfurth -2 Aug. 26, 1930 1,826,760 Foster Oct. 13, 193130 2,292,427 Blackburn Aug. 11, 1942 2,351,183 Blackburn June 13, 19442,465,613 Spaulding Mar. 29, 1949 2,475,103 Mannist July 5, 1949

